[PATCH] D57445: [ARM] Fix TTI IntImmCost

[Sam Parker via Phabricator via llvm-commits]

samparker marked 3 inline comments as done.
samparker added a comment.

I like that idea, I think moving the logic into ARMISelLowering would be good as we already use similar logic there too.



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Comment at: lib/Target/ARM/ARMTargetTransformInfo.cpp:99
+  if (BitWidth - LeadingZeros - TrailingZeros <= 8)
+    return 0;
+
----------------
efriedma wrote:
> Why are you throwing away the existing code using getT2SOImmVal/getSOImmVal and writing out the same logic inline?
Thanks, I'll revert.


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Comment at: lib/Target/ARM/ARMTargetTransformInfo.cpp:108
+    // Use mov and movt
     return 2;
+  }
----------------
efriedma wrote:
> Should this be guarded by useMovt?
Will do.


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Comment at: lib/Target/ARM/ARMTargetTransformInfo.cpp:158
 
+  if (Opcode == Instruction::GetElementPtr) {
+    // FIXME Simplify by assuming 32-bit access, which uses an 8-bit offset
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efriedma wrote:
> Not sure I follow this logic; what does "Imm" actually mean in this case?  Are we expecting that the result of the GEP will be folded into a load?
Yes, I'm assuming an immediate index which will be directly used by a load/store. I know this assumption doesn't hold all the time... But I'm not sure what to do with the limited information here.


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https://reviews.llvm.org/D57445